Saw him on stage about a year ago and he was the most lucid and sensible person there (of the 5 other captains). Avery Brooks certainly was not with it at all.
Well I recall AB getting into some kind of self compelled nonsense and the only person to step up and start talking and change the subject was WS, everyone else was just sitting there gawping.
Because actors are famous for being "lucid and sensible"...?
(This is not a dig at Sir Stewart, I'm just pointing out that the two concepts "working actor" and "lucid/sensible person" are not necessarily linked -- as demonstrated by Brando, Depardieu etc.)
I think the point is simply that if using the title (which is purely optional) then it is standard to use the first name. So Sir Stewart would be somebody else.